US Patent 7868520 Driving apparatus

A driving apparatus includes a piezoelectric element which expands and contracts when a voltage is applied thereto, a driving shaft fixed to one end of the piezoelectric element in an expanding-and-contracting direction, a friction part frictionally engaged with the driving shaft, a lens holder moved along a direction of an optical axis of a lens, and a direction-changing unit which reciprocates the lens holder in the front-rear direction along the optical axis. The direction-changing unit includes a translation cam mechanism including a moving member and a moved member, and converts a linear movement along the expanding-and-contracting direction into a linear movement along the direction of the optical axis.